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13341. 题目: Soil organic matter alteration under biochar amendment: study in the incubation experiment on the Podzol soils of the Leningrad region (Russia)
文章编号: N19052501
期刊: Journal of Soils and Sediments
作者: Nataliya Orlova, Evgeny Abakumov, Elena Orlova, Kirill Yakkonen, Vlada Shahnazarova
更新时间: 2019-05-25
摘要: Purpose: Biochar is one of the most widely used ameliorants for soil amendment, which is known as factor which rises crop yields and levels of soil biological activity. Nowadays, it is under investigated how biochar application affects the dynamics of the humic components and whole soil organic matter (SOM) and the processes of its alteration. This investigation is aimed to evaluate the influence of biochar on the content, composition, and transformation of humic acids (HAs) as the main component of the SOM. Materials and methods: The incubation experiment was carried out on three Podzol Antric soils, with varying amounts of initial total organic carbon. The incubation time was 90 days, using biochar gravimetric doses of 0.1 and 1.0%. The biochar was produced by fast pyrolysis of birch and aspen wood at 550 °С. Humus composition was analyzed for the organic matter fractions extracted with 0.1 M NaOH (containing HAs 1 + fulvic acids (FAs) 1) and 0.1 M Na4P2O7 (containing HAs 1 + FAs 1 + HAs 2 + FAs 2). Isolated HAs were characterized for their elemental composition (C, N, H, and S) and molecular composition with the use of solid-state 13C nuclear magnetic resonance (13C-NMR) techniques. Results and discussion: We found that 0.1% of biochar amendment does not influence SOM mineralization, but 1.0% of biochar increases the mineralization by 15–18%. This process is accompanied by changes in the composition and properties of the HS. The increased proportion of HA aromatic fragments in biochar indicates an increasing of their stability. However, in soils with high humus content and a significant amount of insoluble matter, the processes of mineralization and the growth of HAs are taking place simultaneously. The replenishment of HAs could be the outcome of both the intensification of the transformation processes (mineralization and humification) of the more sustainable insoluble matter compounds and the humification of the biochar itself. Conclusions: The influence of biochar on humification in Podzol Antric soils was revealed on the basis of incubation experiment. Both negative and positive changes under biochar in HS system were demonstrated. The active decrease of humus total contents and also the labile HS ought to qualify as negative changes. The increase of HA chemical maturity that leads to the stability of humus in whole as well as the intensive new HA formation thought to qualify as positive changes.

13342. 题目: Chemical Stability and Transformation of Molybdenum Disulfide Nanosheets in Environmental Media
文章编号: N19052420
期刊: Environmental Science & Technology
作者: Ting-Wei Lee, Chia-Chi Chen, Chiaying Chen
更新时间: 2019-05-24
摘要: Layered transition metal dichalcogenides, including molybdenum disulfide (MoS2), have previously been considered stable in the ambient environment due to the absence of dangling bonds in the electron-filled shells of the end chalcogen atoms. Here, we evaluate the chemical stability of MoS2 nanosheets fabricated by chemical exfoliation (ceMoS2) and surfactant dispersion (sMoS2). The results demonstrate that sMoS2 exhibits greater long-term persistence. Contrarily, ceMoS2 underwent progressive deterioration, in which preferential oxidation of the 1T of a mixture of 1T and 2H phases was observed. The oxidative degradation of ceMoS2 was retarded in the presence of natural organic matter (NOM), including Suwannee River natural organic matter (SRNOM) and Aldrich humic acid (ALHA), in the dark ambient condition, while the aging process of MoS2 with co-occurring ALHA was accelerated under sunlight exposure. The observed inhibition effect on the deterioration of ceMoS2 by NOM was mainly attributed to slower dissolution kinetics with rapid initial oxidation (i.e., forming Mo–O bonding) or carbon grafting, rather than prevention of the formation of secondary small suspended Mo-containing particles. The compiled results highlight that the environmental fate of MoS2 nanosheets will be regulated by the combined effects of exfoliating agents and environmentally relevant factors including organic macromolecules and sunlight exposure.

13343. 题目: Fast Photomineralization of Dissolved Organic Matter in Acid Mine Drainage Impacted Waters
文章编号: N19052419
期刊: Environmental Science & Technology
作者: Chenyi Yuan, Rachel L Sleighter, Linda K. Weavers, Patrick G. Hatcher, Yu-Ping Chin
更新时间: 2019-05-24
摘要: Acid mine drainage (AMD) formed from pyrite (iron disulfide) weathering contributes to ecosystem degradation in impacted waters. Solar irradiation has been shown to be an important factor in the biogeochemical cycling of iron in AMD-impacted waters, but its impact on dissolved organic matter (DOM) is unknown. With a typical AMD-impacted water (pH 2.7–3) collected from the Perry State Forest watershed in Ohio, we observed highly efficient (>80%) photochemical mineralization of DOM within hours in a solar simulator resembling twice summer sunlight at 40°N. We confirmed that the mineralization was initially induced by OH formed from FeOH2+ photodissociation and was inhibited 2-fold by dissolved oxygen removal, suggesting the importance of both the photochemical reaction and oxygen involvement. Size exclusion chromatography and Fourier transform ion cyclotron resonance mass spectrometry elucidated that any remaining organic matter was comprised of smaller and highly aliphatic compounds. The quantitative and qualitative changes in DOM are likely to constitute an important component in regional carbon cycling and nutrient release and to influence downstream aquatic ecosystems in AMD-affected watersheds.

13344. 题目: Co-transformation of Carbon Dots and Contaminant under Light in Aqueous Solutions: A Mechanistic Study
文章编号: N19052418
期刊: Environmental Science & Technology
作者: Xiru Chen, Guodong Fang, Cun Liu, Dionysios D. Dionysiou, Xiaolei Wang, Changyin Zhu, Yujun Wang, Juan Gao, Dong-Mei Zhou
更新时间: 2019-05-24
摘要: In this study, the photochemistry of carbon dots (CDs) and their effects on pollutant transformation were systematically examined. Diethyl phthalate (DEP) degradation was strongly enhanced by CDs under UV light, with the observed reaction rate constant (kobs) increased by 2.4–15.1-fold by CDs at a concentration of 0.5–10 mg/L. Electron paramagnetic resonance (EPR) spectrometry combined with free radical quenching experiments with various chemical probes indicated the production of reactive oxygen species (ROS), including hydroxyl radicals (OH), singlet oxygen (1O2), and superoxide radical anions (O2•–), and these contributed to the enhanced DEP degradation. Meanwhile, CDs were also degraded to low-molecular-weight species and partially mineralized to CO2 by ROS, as evidenced by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and total organic carbon (TOC) analysis, and transformation of CDs was accelerated by DEP. Furthermore, CDs were degraded rapidly under natural sunlight, accompanied by the formation of OH and 1O2. Anions such as CO32–, NO3, and Cl had limited effects on transformation of CDs, while humic substances greatly inhibited this process. Our results indicate that photoreactions of CDs play an important role in influencing the transformation of pollutants and CDs themselves in the natural aquatic environment. The findings provide invaluable information for evaluating risks associated with the release of CDs into the natural environment.

13345. 题目: Leaching of polycyclic aromatic hydrocarbons (PAHs) from sewage sludge-derived biochar
文章编号: N19052417
期刊: Chemical Engineering Journal
作者: Xiaoyang Chen, Lisitai Yang, Satish C.B. Myneni, Yang Deng
更新时间: 2019-05-24
摘要: Polycyclic aromatic hydrocarbons (PAHs), a family of persistent organic pollutants with various negative health effects, are inherently formed during biochar pyrolysis. However, the knowledge regarding the leaching potentials and mechanisms of PAHs remains limited for biochar implementation to soil. In this study we evaluated the leaching behaviors of PAHs from sewage sludge-derived biochar pyrolyzed at different temperatures (300–700 °C) using the protocol of Synthetic Precipitation Leaching Procedure (SPLP) with deionized water. Leachate concentrations of sixteen U.S. Environmental Protection Agency PAHs increased with the increasing pyrolysis temperature, exhibiting an opposite pyrolytic temperature dependence with their concentrations in biochar. The total leachate PAH concentration peaked at 700 °C with 11.75 μg/L, corresponding to 15.9% of total PAHs present in biochar. PAH leaching was associated with the release of hydrophobic organic compounds (HOCs) that created a mobile phase to facilitate the mobilization of PAHs into water. The enhanced release of calcium, aluminum, and barium from the biochars with pyrolysis temperature could also favor the leaching of biochar PAHs, due to the destruction of HOCs-(metal ions)-mineral linkages, which improved the release of HOCs and HOCs-bound PAHs; and because the extent of metal cross-linking in biochar is reduced, enabling better diffusion of PAHs through the inner matrix and thus accelerating their desorption.
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13346. 题目: Biochar for environmental management: Mitigating greenhouse gas emissions, contaminant treatment, and potential negative impacts
文章编号: N19052416
期刊: Chemical Engineering Journal
作者: Chen Zhang, Guangming Zeng, Danlian Huang, Cui Lai, Ming Chen, Min Cheng, Wangwang Tang, Lin Tang, Haoran Dong, Binbin Huang, Xiaofei Tan, Rongzhong Wang
更新时间: 2019-05-24
摘要: With increased interest in scientific investigations and large-scale applications of lignocellulosic biomass derived biochar for environmental management, a comprehensive understanding of its function in the fragile earth environment is urgently needed. The study on the relationship between biochar properties and potential applications requires continuing research. This review provides new insights into the state-of-the-art accomplishments in the utilization of biochar in environmental management and covers three perspectives: firstly, mitigation of greenhouse gas (GHG) emissions, such as sequestration of CO2 and CH4 in global carbon pools and mitigation of N2O emissions; secondly, pollution control, including adsorptive removal and reactive removal of inorganic and organic contaminants; thirdly, potential negative aspects of biochar applications, including contaminations originated from biochar, negative alterations to soil properties and soil biota, negative impacts of biochar on GHG emissions and negative impacts of biochar migration. From a unique and comprehensive environmental perspective, this article aims to provide a critical review of updated knowledge on both positive and negative impacts of biochar for environmental management, based on an exponentially increased number of publications on the topic over the past decade.
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13347. 题目: Kinetics and pathway of atrazine degradation by a novel method: Persulfate coupled with dithionite
文章编号: N19052415
期刊: Chemical Engineering Journal
作者: Wei Song, Ji Li, Caixia Fu, Zhuoyue Wang, Xiaolei Zhang, Jingxin Yang, William Hogland, Ling Gao
更新时间: 2019-05-24
摘要: Efficient and environmentally friendly activation methods of persulfate (PS) have gained growing attention in the remediation of water or soil polluted by organic contaminants. Among all, the exploration of effective and applicable method for the PS activation becomes one of the hottest topics in the field of organic degradation. Dithionite (DTN) was employed in this study to activate PS and applied to degrade Atrazine (ATZ) without secondary pollution. ATZ could be completely degraded within 90 min by PS/DTN system. ATZ degradation by PS obeyed the pseudo-first-order kinetics and the rate constant values increased from (4.71–5.05) × 10−3 min−1 to (4.59–5.09) × 10−2 min−1 with the addition of DTN. Sulfate radicals were verified to be the dominant reactive species through the radical scavenging experiment. PS/DTN system can remain a strong oxidative ability in the range of pH below 9.0. The presence of Cl, natural organic matter (NOM), and high concentration of HCO3 may inhibit the removal of ATZ while the low concentration of HCO3 can slightly promote the degradation. It was found that the degradation pathways of ATZ by PS/DTN involved de-chlorination and hydroxylation, de-alkylation, and de-amination by the reactive species. The study reveals that PS/DTN system has the broad application prospect in the treatment of refractory pollutants.
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13348. 题目: The influence of the UV/chlorine advanced oxidation of natural organic matter for micropollutant degradation on the formation of DBPs and toxicity during post-chlorination
文章编号: N19052414
期刊: Chemical Engineering Journal
作者: Jianliang Sun, Dezheng Kong, Ehsan Aghdam, Jingyun Fang, Qianyuan Wu, Jiajian Liu, Ye Du, Xin Yang, Chii Shang
更新时间: 2019-05-24
摘要: This study compares the influences of UV/chlorine and UV/H2O2 advanced oxidation of natural organic matter at the equivalent degradation of two model micropollutants on the formation of disinfection by-products (DBPs) and toxicity during post-chlorination. At 90% degradation of carbamazepine, the UV/chlorine advanced oxidation process (AOP) at pH 6.0 (3.0 mg/L chlorine and 280 mJ/cm2) resulted in comparable yields of dichloroacetic acid, trichloroacetic acid, chloroform, chloral hydrate, dichloroacetonitrile, trichloropropanone and total organic chlorine (TOCl) during the post-chlorination, compared to the UV/H2O2 AOP (8.0 mg/L H2O2 and 280 mJ/cm2). The UV/chlorine AOP increased the chloroacetic acid yields by 28–43% at pH 7.0 and 8.0. The cytotoxicity with the UV/chlorine AOP was 32% lower than with the UV/H2O2 AOP, however, the genotoxicity was similar. At the 90% degradation of atrazine, the UV/chlorine AOP (6.0–13.9 mg/L chlorine and 750–1000 mJ/cm2) increased the chloroacetic acid yields by 35–81% but did not increase the yields of other four known DBPs and TOCl, compared to the UV/H2O2 AOP (8.0–12.9 mg/L chlorine and 750–1000 mJ/cm2). The cytotoxicity and genotoxicity with the UV/chlorine AOP at pH 6.0 were 22–27% lower than those with the UV/H2O2 AOP, likely due to the selective destruction of the precursors of cytotoxic and genotoxic DBPs by RCS. The TOCl yields were positively correlated to the decreases in the specific UV absorbance at 254 nm and humic-like fluorescence. The TOCl yields exhibited a linear relationship with the genotoxicity (R2 = 0.81) but were weakly correlated with the cytotoxicity (R2 = 0.40). Although the UV/chlorine AOP increases the formation of some DBPs under certain circumstances, compared to the UV/H2O2 AOP, it does not enhance the genotoxicity and even decreases the cytotoxicity.
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13349. 题目: Glycine transformation induces repartition of cadmium and lead in soil constituents
文章编号: N19052413
期刊: Environmental Pollution
作者: Yulong Zhang, Shuran He, Zhen Zhang, Huijuan Xu, Jinjin Wang, Huayi Chen, Yonglin Liu, Xueli Wang, Yongtao Li
更新时间: 2019-05-24
摘要: Heavy metal stress in soil accelerates the plant root exudation of organic ligands. The degradation of exudate ligands can be fundamental to controlling the complexation of heavy metals. However, this process remains poorly understood. Here, we investigated the relationship between the transformation of glycine, a representative amino acid exudate, and cadmium/lead mobility in soils. Two 48-h incubation experiments were conducted after glycine addition to the soils. Parameters related to glycine distribution and degradation, Cd/Pb mobility, and the formation of glycine-Cd complex were analyzed. Glycine addition gradually decreased the Cd and Pb mobility throughout the 48-h incubation. By the end of the experiment, the CaCl2-extracted Cd and Pb concentrations decreased by 63.5% and 43.6%, respectively. The glycine mineralization was strong in the first 6 h, as indicated by a sharp decrease in CO2 efflux rates from 10.04 ± 0.62 to 3.51 ± 0.07 mg C–CO2 kg−1 soil h−1. The mineralization rates notably decreased after 6 h. The comparisons of dissolved organic carbon and hydrolyzable amino acid contents indicated that glycine mineralization in solution (95.6%) was much stronger than that in soil solids (49.3%). At the end of incubation, 0.22 mmol kg−1 glycine remained in soil solids. The remaining glycine provided sufficient sorption sites for Cd2+ and Pb2+, resulting in enhanced metal fixation via complexation. Comparisons of zeta potentials supported the formation of the glycine-Cd complex. The Cd and Pb immobilization processes could be attributed to metal-glycine complex formation, sorption re-equilibrium, and glycine degradation. These findings emphasize that the biogeochemical processes of glycine, derived from root exudates or protein degradation products, increased the sorption of heavy metals to soils and thus reduced their toxicity to plants.
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13350. 题目: Dithiothreitol (DTT) concentration effect and its implications on the applicability of DTT assay to evaluate the oxidative potential of atmospheric aerosol samples
文章编号: N19052412
期刊: Environmental Pollution
作者: Manfei Lin, Jian Zhen Yu
更新时间: 2019-05-24
摘要: The cell-free dithiothreitol (DTT) assay is widely used and the DTT consumption rate is interpreted to assess the oxidative potential (OP). Most researchers use an experimental procedure developed by Cho et al. (2005) while some adopt a procedure by Li et al. (2009). The key difference between the two procedures is the initial DTT concentration, 100 μM used in the former and 20 μM in the latter, raising an unaddressed issue of comparability. We examine in this work this issue using metal-free humic-like substance (HULIS) samples isolated from ambient aerosol and two metals (i.e. copper and manganese). We found that higher initial DTT concentrations led to higher DTT consumption rates for both HULIS and metals. For HULIS, the increase in DTT consumption rate was proportional to the initial DTT concentration (i.e., roughly by 5-fold), allowing correction of the concentration effect and direct comparison of results from the two protocols. However, the proportionality did not hold for the metals or metal-organic mixtures. The increase was much lower than the proportionality of 5 and metal concentration-dependent, specifically, 1.2–1.3 for Cu and from negligible to 2.0 for Mn. For six water extracts of ambient aerosol samples, in which HULIS and metals co-exist, the proportionality ranged from 1.3 to 2.2. This deviation from a linear dependence on initial DTT concentration, plausibly due to metal-DTT binding, impedes assessing and comparing OP of metals and metal-organic mixtures using different implementations of the DTT assay. Considering the different antioxidants concentrations in real human lung fluid, this work raises caution about using the DTT assay to assess metal-containing mixtures, such as ambient aerosol samples.
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13351. 题目: Biochar-induced soil stability influences phosphorus retention in a temperate agricultural soil
文章编号: N19052411
期刊: Geoderma
作者: Vanita Sachdeva, Naseer Hussain, Barry R. Husk, Joann K. Whalen
更新时间: 2019-05-24
摘要: Surface runoff from agricultural fields is the largest non-point source of phosphorus (P) that pollutes surface water in humid temperate regions. Best management practices have attempted to reduce P loading and improve P retention in agricultural soils, but significant losses continue to occur, emphasizing the need for novel solutions. The objective of this study was to determine whether wood-based biochars applied to an agricultural field, 3 years earlier, could reduce P loss in surface runoff by increasing water infiltration or by improving soil stability. Field plots amended with Dynamotive, Basques and Pyrovac biochars (5 and 10 t ha−1) or without biochar were subjected to 30-min of simulated rainfall to determine runoff volume, time-until-ponding, infiltration rate, and water holding capacity, as well as the P concentration and P load in runoff. The distribution of soil macro- and micro-aggregates and their total organic C and total P content was measured. Soil water dynamics were not affected by biochar amendments, however, runoff contained significantly less ortho-P in field soil amended with Dynamotive and Basques biochar at 5 t ha−1 and significantly less particulate P when amended with biochar at 10 t ha−1. Biochar-amended soil had significantly greater microaggregate stability, organic C and total P content than the control soil without biochar. The reduction in particulate P concentration in runoff may be the result of biochar integration within the microaggregate structure, which indirectly promotes P retention in macroaggregates.

13352. 题目: Facilitated transport of cadmium by biochar-Fe3O4 nanocomposites in water-saturated natural soils
文章编号: N19052410
期刊: Science of The Total Environment
作者: Ming Chen, Xinyi Tao, Dengjun Wang, Zibo Xu, Xiaoyun Xu, Xiaofang Hu, Nan Xu, Xinde Cao
更新时间: 2019-05-24
摘要: Herein we explored the co-transport behaviors of cadmium (Cd2+) with biochar-Fe3O4 nanocomposites (BFNCs) (and biochar-alone for comparison) in water-saturated natural soil (paddy soil and red soil) packed columns. The BFNCs promoted the transport of Cd2+ (Cd2+ mass recovery = 2.71–10.5%) by 2.5-times in soils, compared to the biochar-alone (Cd2+ mass recovery = 1.28–4.07%). Greater interplays via electrostatic attraction, complexation with hydroxyls, and π-π interaction with the aromatic complexes altogether contributed to the higher adsorption capacity and transport potential towards Cd2+ by the BFNCs (vs. biochar-alone). The BFNCs greatly increased (27.1–95.5 times) Cd2+ transport in soils mainly through BFNC-Cd2+ complexes, compared to the negligible transport of Cd2+ in soils without presence of BFNCs. Higher mobility of BFNCs and BFNC-Cd2+ complex occurred in the red soil than in the paddy soil due to the lower contents of Fe/Al oxides in the red soil. Greater enhancement effect (~2.5 times) on Cd2+ was observed by BFNCs derived from wheat straw than wood chip, due to the stronger sorption ability of wheat straw biochar towards Cd2+, likely stemming from more mineral composition such as CaCO3. Our findings suggest that the potential co-transport risks should not be simply ignored particularly when the next-generation of multifunctional biochar‑iron oxide nanocomposites are employed for in-situ remediation of soils contaminated with organic/inorganic contaminants like Cd2+.
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13353. 题目: Long-term fertilization and manuring with different organics alter stability of carbon in colloidal organo-mineral fraction in soils of varying clay mineralogy
文章编号: N19052409
期刊: Science of The Total Environment
作者: Ruma Das, T.J. Purakayastha, Debarup Das, Nayan Ahmed, Rahul Kumar, Sunanda Biswas, S.S. Walia, Rohitashav Singh, V.K. Shukla, M.S. Yadava, N. Ravisankar, S.C. Datta
更新时间: 2019-05-24
摘要: Majority of organic matter is bound to clay minerals to form stable colloidal organo-mineral fraction (COMF) in soil. Stability of carbon (C) in COMF is crucial for long-term C sequestration in soil. However, information on the effect of long-term fertilization and manuring with various organic sources on C stability in such fraction in soils with varying clay mineralogy is scarce. The present study was, therefore, carried out to assess the effect of thirty-one years of continuous fertilization and manuring with different organics on C-stability in COMF extracted from an Inceptisol, a Vertisol, a Mollisol, and an Alfisol. The treatments comprised of control (no fertilization), 100% NPK (100% of recommended N, P and K through fertilizer), 50% NPK+ 50% of recommended N supplied through either farm yard manure (FYM) or cereal residue (CR) or green manure (GM). The stability of C (1/k) in COMF was determined from desorption rate constant (k) of humus-C by sequential extraction and correlated with extractable amorphous Fe-Al-Si-oxides, and crystallite size of illite minerals. Long-term fertilization and manuring with the above sources of organic altered the contents of amorphous Fe-Al-Si-oxides, and decreased the crystallite size of illite in all the soil orders. Fifty percent substitution of fertilizer nitrogen by various organics significantly increased C-stability in COMF by 27–221% (mean 111%) over full dose of NPK (100% NPK). Smectite dominating Vertisol exhibited highest stability of C followed by the Mollisol, the Inceptisol and the Alfisol. Stability of such C in soil was correlated positively with the amount of amorphous Fe and Al oxides but negatively with crystallite size of illite (r = −0.46, P < 0.01). Application of NPK + GM or NPK + FYM in Inceptisol, Vertisol and Mollisol and NPK + GM or NPK + CR in Alfisol emerged as the best management practices for higher stabilization of C in COMF for long-term C sequestration.
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13354. 题目: Infrared spectroscopy as a useful tool to predict land use depending on Mediterranean contrasted climate conditions: A case study on soils from olive-orchards and forests
文章编号: N19052408
期刊: Science of The Total Environment
作者: Ninon Delcourt, Catherine Rébufa, Nathalie Dupuy, Nathalie Boukhdoud, Caroline Brunel, Juliet Abadie, Isabelle Giffard, Anne Marie Farnet-Da Silva
更新时间: 2019-05-24
摘要: Soil chemical properties depend on various environmental factors such as above ground vegetation, climate and the parent rock substratum. Land use, and the associated management practices, is one of the major drivers which can deeply impact soil properties. To better understand the dynamics of soil chemical properties and to assess potential impact of land use, an improved monitoring of chemical signature in organo-mineral topsoils is necessary. Here, we explored how land use (forests or agrosystems i.e. olive-tree orchards) may shape soil chemical signature and whether it depends i) on the type of agricultural or sylvicultural practices, ii) on contrasted Mediterranean climate conditions at different spatial scales. We measured variations in soils properties by FTIR-ATR (Fourier-Transformed Infrared – Attenuated Total Reflectance) spectroscopy and elemental concentrations. FTIR showed that the aromatic fraction of organic matter and CaCO3 discriminated soils under different land uses (orchards or forests) and this depended on climate (sub-humid vs humid climate). Moreover, the chemical signatures of soils varied with the practices applied. For agrosystems, soils complemented with olive-mill wastes were characterized by aromatics compared to soils under natural grass or tillage. For forests, soils from Pinus spp. stands and Quercus spp. stands were discriminated by CaCO3 and aromatics respectively. Contrasted climate conditions at local scale, i.e. northern vs southern slopes for forests and distance from the sea (coastal vs inland area) for agrosystems, had an effect on soil chemical signature. The AcomDIM interpretation of FTIR-ATR signals showed that factors “land use”, “practices” and “climate” and their interactions could have a significant impact on soil chemical signature. PLS modeling also confirmed that FTIR-ATR is a useful tool to predict a type of land use depending on climate.
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13355. 题目: Physical, biochemical, and microbial controls on amino sugar accumulation in soils under long-term cover cropping and no-tillage farming
文章编号: N19052407
期刊: Soil Biology and Biochemistry
作者: Lidong Li, Candace B. Wilson, Hongbo He, Xudong Zhang, Feng Zhou, Sean M. Schaeffer
更新时间: 2019-05-24
摘要: Understanding the processes controlling amino sugar accumulation in soil is essential for predicting the contribution of microbial residues to soil organic matter (SOM). The accumulation of amino sugars in soil is affected by multiple factors. Seldom are those factors examined together. We measured amino sugar concentration, extracellular enzyme activity, microbial respiration rate, and soil aggregate composition in an agricultural soil under 33-years of conservation management. The accumulation patterns of different amino sugars under the effects of no-tillage farming and cover cropping were compared and contrasted. The relative importance of physical, biochemical, and microbial controls of amino sugar accumulation was quantified using structural equation modelling. Our results show that although different types of amino sugars exhibited similar accumulation patterns in soil, their stabilization mechanisms might vary as demonstrated by structural equation models. The structural equation models indicate that macroaggregates had the largest total effect (0.59, P < 0.05) on muramic acid, and microbial respiration rate and wheat cover crops had large total effects (0.50 and −0.48 respectively, P < 0.05) on glucosamine. These results suggest that physical protection of soil aggregates played a critical role in muramic acid stabilization in soil, while microbial activity and nutrient condition were more critical for glucosamine. We also observed 24%–35% of decreases in soil amino sugars when nitrogen (N) was scarce and carbon (C) was excessive, concomitant with increases of extracellular enzyme activities. These results may support the theoretical model of microbial N mining. Structural equation model indicates that β-N-acetylglucosaminidase (NAG) had a negative effect on total amino sugars (−0.41, P < 0.05) and soil N had a negative effect on NAG (−0.27, P < 0.05). These results suggest that amino sugars can be decomposed by NAG as an alternative N source for microbes when readily available N was low. Leucine aminopeptidase (LAP) had a positive total effect on total amino sugars and a negative total effect on NAG (0.26 and −0.26 respectively, P < 0.05). This indicates that decomposition of amino acids by LAP may be a preferred strategy prior to decomposition of amino sugars by NAG to meet N requisition.

13356. 题目: Impact of plateau pika ( Ochotona curzoniae ) burrowing-induced microtopography on ecosystem respiration of the alpine meadow and steppe on the Tibetan plateau
文章编号: N19052406
期刊: Plant and Soil
作者: Jingxue Zhao, Lihua Tian, Haixia Wei, Tao Zhang, Yanfu Bai, Ruicheng Li, Yanhong Tang
更新时间: 2019-05-24
摘要: Background: Alpine ecosystem underlain by permafrost is considered as one of the most vulnerable ecosystems to disturbance, especially the alpine grassland on the Tibetan plateau with an altitude above 4000 m. Plateau pika (Ochotona curzoniae) burrowing can create distinctive bare grounds and cause micro-topographical heterogeneity in alpine grasslands. The burrowing-induced changes in microtopography may directly alter plant and soil interactions as well as ecosystem carbon cycle, which have rarely been studied in Tibetan alpine grasslands. Methods: To test the responses of ecosystem respiration (Re) to pika burrowing-induced changes in microtopography, we investigated plant characteristics, soil properties and Re from the bare grounds and vegetated grounds in the alpine meadow and steppe on the Tibetan Plateau. Results: Our study showed that vegetation cover, species richness, plant biomass, soil moisture (SM), soil organic carbon (SOC), total nitrogen (STN), soil microbial biomass carbon (MBC) and nitrogen (MBN) in the bare grounds were significantly lower than in the vegetated grounds in both alpine meadow and alpine steppe (P < 0.05). However, soil temperature and inorganic nitrogen tended to increase in the bare grounds. The growing season Re was significantly lower in the bare grounds than that in the vegetated grounds (P < 0.01). Pika burrowing had negative effects on Re and its temperature sensitivity in both alpine vegetations (P < 0.05). The relative changes in Re due to burrowing-induced changes in microtopography were positively correlated with the burrowing caused changes of AGB, BGB, SOC and MBC (P < 0.05). Pika burrowing-induced changes in soil temperature, soil moisture, plant biomass and microbial biomass are the major factors for the decrease of Re in the bare grounds. Conclusion: In view of the large number of pika burrows in the alpine grasslands and the loss of soil organic carbon due to pika bioturbation, the impacts of pika burrowing-induced changes in microtopography on Re must be considered in predicting the carbon cycle in alpine grasslands.

13357. 题目: Boreal tree species affect soil organic matter composition and saprotrophic mineralization rates
文章编号: N19052405
期刊: Plant and Soil
作者: Javier H. Segura, Mats B. Nilsson, Tobias Sparrman, Henrik Serk, Jürgen Schleucher, Julie Tolu, Mats G. Öquist
更新时间: 2019-05-24
摘要: Aims: To investigate how different tree species affect the composition of SOM and its mineralization in boreal forest ecosystems. Methods: We used pyrolysis GC–MS for molecular-level characterization of the SOM formed under five common boreal tree species at a replicated field experiment ~50years after plantation. We incubated soil samples at 4, 9, 14 and 19 °C and measured inherent CO2 production and substrate-induced respiration. We then evaluated if the saprotrophic microbial activity and its temperature sensitivity was controlled by the SOM composition. Results: The molecular composition of the SOM emerged as key factor influencing SOM properties in plots with different tree species. Most of the variance in the SOM content was explained by the organo-chemical composition of the SOM. More importantly, the fraction of the microbial community able to utilize the native SOM was largely controlled by the SOM organo-chemical composition. Temperature sensitivity of CO2 production (Q10) was not explained by SOM composition. However, the microbial access to different SOM pools varied with temperature. Conclusions: These results bridge the gap between the paradigms of short-term litter and long-term SOM decomposition showing that, on an intermediate timescale (~50 years), boreal tree species affect SOM molecular composition and saprotrophic mineralization rates.

13358. 题目: Soil salinity and land use-land cover interactions with soil carbon in a salt-affected irrigation canal command of Indo-Gangetic plain
文章编号: N19052404
期刊: CATENA
作者: Ajay Kumar Bhardwaj, Vinay Kumar Mishra, Atul Kumar Singh, Sanjay Arora, Shefali Srivastava, Yash Pal Singh, Dinesh Kumar Sharma
更新时间: 2019-05-24
摘要: Soil salinity poses a threat to the sustainable management of agricultural landscapes and has an effect on soil carbon storage. This study investigated land use-land cover (LULC) relations with soil organic carbon (C) in a salinity-infested landscape with inter-spun vegetated and non-vegetated land area. A sodicity infested command area (~100 ha) along Sharda Sahayak canal in Uttar Pradesh, India was selected for studying LULC effects on soil organic carbon (C) and soil properties to 60 cm soil depth. The area was divided in a grid of 100 m × 100 m, and soils were sampled and analyzed at 140 geo-referenced points representing five LULC classes. The LULC dominant in the representative area were barren-coverless (BC), barren-grass cover (BG), rice-fallow (RF), rice-wheat (RW), and rice-okra-mentha (ROM). Soil organic C decreased with depth, decreased with increase in soil pH, and decreased with an increase in exchangeable sodium percentage (ESP). The effects were highly significant in surface layers (0–0.3 m). Similarly with electrical conductivity (EC) too, soil organic C had a negative correlation. Soil organic C varied significantly with LULC. The soil organic C content decreased in the order: ROM > RW > RF > BG > BC. As the intensity of crop/plant cover increased, the soil salinity (ESP, pH and EC) decreased. The average soil ESP was maximum in BC (44%) followed by BG (30%), RF (15%), RW (8.5%), and ROM (7.0%). The cumulative probability trends indicated the probability of lesser ESP with increased vegetative cover/primary productivity. A strong (p < 0.001), a negative relationship was observed between soil organic C and pH in rice-based systems. Analysis of soil organic C stock with depth for the studied LULCs indicated 4–70% (grass cover to rice-wheat cropping sequence) increase in total soil organic C stock just by supporting vegetative cover on barren sodic land. The study was indicative of scope for soil C sequestration and reclamative effects in salt-affected areas of Indo-Gangetic region by adopting appropriate land use strategies, which may include the adoption of rice-based and grass-based cropping systems, to check the development of sodicity in soils.

13359. 题目: Can glomalin content be used as an indicator for erosion damage to soil and related changes in organic matter characteristics and nutrients?
文章编号: N19052403
期刊: CATENA
作者: Bořivoj Šarapatka, Diana Patricia Alvarado-Solano, David Čižmár
更新时间: 2019-05-24
摘要: Erosion is a serious global problem for agricultural land and agroecosystems in general. In the Czech Republic (CZ) erosion affects approximately two-thirds of total agricultural land. In order to evaluate the influence of erosion processes on soil properties, besides traditional parameters relating to soil organic matter, we also focused on glomalin as a product of mycorrhizal fungi and on spores of such fungi. The aim was to verify the sensitivity of this parameter to changes in the soil environment as a result of soil degradation, how it correlates with other soil characteristics, and how useful it is for indicating changes in soil properties. The research was carried out on 48 localities in erosion-threatened areas of Southern Moravia, CZ. Erosional, depositional and control (source) sites located on different slopes were selected using erosion-deposition models. Most statistically significant differences were recorded between erosional and depositional sites, the latter showing higher concentrations in both glomalin and characteristics relating to soil organic matter and content of nutrients. Comparison between source and erosional sites also showed statistically significant differences – higher values of both glomalin and characteristics relating to the quantity and quality of soil organic matter were found in source areas. Moreover, we also found statistically significant differences in the number of arbuscular mycorrhizal fungi (AMF) spores. On the other hand, no statistically significant differences in selected nutrients were found between control and erosional sites. Within our research, source areas did not differ significantly from those of deposition. In evaluating all results, strong correlations were found especially between glomalin and the quantity and quality of organic matter. It was in relation to glomalin that the most correlations were found to the other tested parameters. Our results suggest the possibility of using glomalin values in determining changes in soil properties during degradation processes, e.g. soil erosion.

13360. 题目: Enhanced ciprofloxacin removal by sludge-derived biochar: Effect of humic acid
文章编号: N19052402
期刊: Chemosphere
作者: Kun Luo, Ya Pang, Qi Yang, Dongbo Wang, Xue Li, Liping Wang, Min Lei, Jiamei Liu
更新时间: 2019-05-24
摘要: Humic acid (HA) is ubiquitous in the environment, and its effect on the adsorption of pollutants onto biochar (BC) has been widely investigated. However, the catalytic degradation of organic contaminants induced by persistent free radicals (PFRs) in BC is not negligible. In this study, two different source of external HA, dissolved HA and coated HA, was employed to assess the effect of HA on the degradation of organic contaminant ciprofloxacin (CIP) by PFRs in BC. Results showed that relatively low concentration of dissolved HA promoted the removal of CIP from 59.78% (control) to 66.70% (5 mg/L dissolved HA) by BC, but higher concentration of dissolved HA inhibited. By contrast, coated HA altered the characteristics of BC and had negative impact on organics removal. The removal of CIP by BC in the presence of HA did not have a great difference at pH 6–9, and increasing dissolved oxygen promoted CIP degradation. In addition, the contribution of CIP removal led by adsorption was 47.61%, 41.62% and 47.84% respectively for BC, BC + dissolved HA and 1% HA coated BC. Correspondingly, the contribution of CIP removal led by •OH induced from PFRs in BC was respectively 21.88%, 35.58% and 25.11%, and the contribution led by PFRs themselves oxidation was 30.51%, 22.80% and 27.05%, respectively. The calculated contributions of adsorption and degradation to CIP removal demonstrated that the contribution of degradation to CIP removal led by •OH increased, while the contribution led by PFRs themselves oxidation was inhibited in the presence of dissolved and coated HA.

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